1. Field of the Invention
The present invention relates to a rechargeable cell, which is smaller in diameter and height than a general dry cell having standardized dimensions, contained in an insulated case to conform to the general dry cell in size.
2. Description of the Prior Art
U.S. Pat. No. 3,684,583 discloses a rechargeable battery, which is interchangeable in configuration with a general dry cell. This rechargeable battery is formed by a rechargeable cell which is smaller in diameter and height than a general dry cell having standardized dimensions, an insulated cylindrical case and auxiliary terminals.
FIG. 1A is a longitudinal sectional view showing the conventional rechargeable battery disclosed in the above Patent. FIG. 1B is a partially fragmented sectional view of the conventional battery seen from a negative terminal side. FIG. 1C is a plan view of the conventional battery seen from an positive terminal side. Referring to FIG. 1A, a rechargeable cell 1 having smaller dimensions than those of a SUM-1 (D-size) dry cell is provided with a positive terminal 2, to which a first auxiliary terminal 3 formed by a tubular member is rigidly fixed thereby to increase the vertical size. A second auxiliary terminal 5, which is formed by a dished member having a larger diameter than that of the cell 1, is welded to a bottom portion 4 of the cell 1, thereby to increase the radial size.
An end wall 7 is provided on an insulated cylindrical case 6 of plastic. The end wall 7 is provided with an opening 8 for receiving the first auxiliary terminal 3. The other end of the case 6 is closed by the second auxiliary terminal 5.
Referring to FIG. 1B, radial ribs 9 are integrally formed on the inner wall of the case 6, thereby to support the cell 1 in the radial direction.
In such a conventional battery, the first auxiliary terminal 3 is directly mounted on the positive terminal 2 of the cell 1, but not rigidly fixed to the case 6. Therefore, impact or stress applied to the first auxiliary terminal 3 is directly transmitted to the positive terminal 2 of the cell 1. Thus, when such a battery is connected to/disconnected from a battery charger or a battery housing of a battery-applied device, or the same is thrown down by accident, impact or stress applied to the first auxiliary terminal 3 is directly transmitted to the positive terminal 2 of the cell 1 to exert a bad influence on a safety vent provided on the positive terminal 2, to disable correct maintenance of working pressure of the vent.
FIG. 2 is a longitudinal sectional view showing another conventional rechargeable battery, which contains a plurality of cells. This battery is disclosed in U.S. Pat. No. 4,489,268. Referring to FIG. 2, a cylindrical case 11 contains a plurality of rechargeable cells 12a, 12b and 12c. Conductive plates, which are not shown in FIG. 2, are provided between cell 12a and cell 12b and between cell 12b and cell 12c respectively to connect each other. A positive auxiliary terminal 14 for supplying power is provided on one end of the case 11, while a negative auxiliary terminal 16 is provided on the other end thereof. A charging terminal 13 is provided on a circumferential surface part, which is close to the positive auxiliary terminal 14, of the case 11. A lead member 15 electrically connects the positive terminal of the cell 12a to the positive auxiliary terminal 14 and the charging terminal 13. The positive auxiliary terminal 14 is held by a positive terminal holding part 17. The case 11 is formed by the positive terminal holding part 17, a cylindrical part 18 radially supporting the cells 12a, 12b and 12c and a negative terminal bottom surface part 19 for holding the negative auxiliary terminal 16. The positive terminal holding part 17, the cylindrical part 18 and the negative terminal bottom surface part 19 are formed of insulating resin materials.
The ring-shaped charging terminal 13 is welded to the lead member 15 through an opening 17a defined in the peripheral edge of the positive terminal holding part 17. The positive auxiliary terminal 14 is electrically connected with the lead member 15, to be held by the positive terminal holding part 17 by an eyelet. The negative auxiliary terminal 16 is electrically connected to a negative terminal of the cell 12c by spot welding or the like. The negative auxiliary terminal 16 is inserted in the cylindrical part 18 of resin to adhere the negative terminal bottom surface part 19, having an opening in its center, to the cylindrical part 18 by ultrasonic welding or the like. The positive terminal holding part 17 is also adhered to the cylindrical part 18 by ultrasonic welding or the like.
In this conventional battery, strength for holding the positive auxiliary terminal 14 is insufficient since the positive auxiliary terminal 14 is fixed to the auxiliary terminal holding part 17 by the eyelet. When, for example, the battery is dropped with the positive auxiliary terminal 14 being downwardly directed, force is directly applied to the positive auxiliary terminal 14 to break a part joined by the eyelet. Further, this battery has a large number of components to require a number of steps for assembling, leading to various restrictions.